Disordered flow in blood vessels may be detected be velocity measurements, offering a potential indicator of localized atherosclerotic plques at an early stage of development. These measurements must be performed noninvasively to be of clinical value. The plused ultrasonic Doppler velocity meter is noninvasive but in its present development lacks the frequency response necessary to measure tubulence and disordered flows. The prrposed work is aimed at development of Doppler ultrasound signal processing methods which will allow noninvasive turbulent blood flow studies. The research is in two parts: (1) refinement of a phase-lock loop system for turbulence measurements and (2) development of a digital signal processing system centered around the minicomputer- based HP 5451B Fourier Analyzer. These are supported by theoretical and experimental research into the statistical characteristics of the scattering volume.